Known process for the manufacture of bisphosphine oxide compounds or bisphosphonates of general formulae I and II are two-stage processes. In the first stage a compound of formula Ia or Ia set forth below is converted into the corresponding iodide or bromide with iodine or bromine at about -70.degree. C. in the presence of a lithium dialkylamide. A reagent which yields iodine or bromine, such as e.g. N-iodo- or bromo-succinamide, 1-iodo-2-chloroethane, 1,2-dibromomethane and the like, can also be used in place of iodine or bromine.
Starting materials of formula Ia or IIa in which R.sup.4 signifies C.sub.1-8 -alkoxy or phenoxy can also be reacted with an alkyllithium solution, preferably butyllithium solution or sec.butyllithium solution, in the presence of catalytic amounts of an amine, such as e.g. diisopropylamine. If desired, an additional tert.amine, such as e.g. N,N,N',N'-tetramethyldiamine, is added.
Starting materials of formula Ia or IIa in which R.sup.4 signifies phenyl, substituted phenyl, naphthyl, substituted naphthyl, heteroaryl or substituted heteroaryl can also be reacted with an aryllithium solution, preferably phenyllithium solution, or an alkyllithium solution, preferably tert-butyllithium solution.
In a second step the aryl halide is converted into a biaryl compound at 110.degree. C. to 200.degree. C. in the presence of copper(0) (Ullmann coupling).
This two-stage process is not very suitable for implementation on an industrial scale. The first stage must be carried out at low temperatures and gives the aryl halide in a yield of about 70%. Precipitates of byproducts which occur can give rise to difficulties. On the other hand, the second stage must be carried out at high temperatures and requires stoichiometric amounts of copper, with the Ullmann coupling also being unfavourable from ecological points of view.
The object of the invention is to provide an improved process for the manufacture of bisphosphine oxide compounds and bisphosphonates.